Hi,
I wonder if someone can confirm if below is possible or not, using the
Atlas facilities QGIS 3.20.3 in WIndows 10.
Two issues, the second relying on the first.
*#1 Variable size Map Item.*
I would like to vary the size of the Map Item window, depending on the
zoom window of the Atlas page.
I can set the "Position and Size" using an Expression or an attribute
Field, but this seems to be fixed rather than dynamic
ie: Is it possible to have Expression and/or Field values dynamic per
Atlas coverage page?
*#2 Multiple Sub-maps per MapSheet.*
Is it possible to have an Atlas page layout such that (say) in the top
half of the page you have your zoomed map (as in #1 above) and in the
bottom half of that sheet-page you place n-mapboxes as insets
predefined as n-AOI rectangles inside the zoom-window in the top of this
MapPage?
*A practical example/use would be:*
Say you are doing an aerial analysis of a stretch of river and you have
identified areas of interest by placing oriented rectangles around them.
You now want to show an overview of segments of the river, and then a
zoom-in to each identified AOI rectangle to show larger scale prints
below this river segment.
*
**Method could/would be to:*
Using the width of your intended page size, calculate the length of
river you can fit across 1 page of your Atlas. Let's assume 1Km
Now a river meanders so you cannot run down the polyline depicting
the river, you need to rotate and cut the river to the width of your
atlas page.
This means your atlas Map-Item width will be constant, but the
height, due to curvatures in the river, will vary.
Once you have your oriented MBRs calculated along the river, you can
use these as your Atlas Coverage layer.
To show this with optimal page-area usage, you would need the Atlas
facility I describe in *#1 above*.
Now, along the river you will have pre-placed your oriented AOI
rectangles.
These will be much smaller rectangles than the 1Km river-length
Atlas Coverage rectangles.
Now, for each AOI rectangle inside the current 1Km coverage
rectangle, I want to show a larger scale image below the current
coverage rectangle.
If*#2 above* was possible and flexible, one could use the calculated
(current) bottom left paper coord of the coverage rectangle to
calculate the top-left position of the first AOI area.
And so on across then down the remaining Atlas page for subsequent
AOI boxes, which will likely be of varying size.
I suppose this is rather like wanting an Atlas page-set within and Atlas
page.
Anyone achieved something like this?
Does this sound useful?
I guess, unless I've missed some facility in Atlas, I will be doing this
by using the Atlas facility to spit out carefully named jpeg images, and
then assembling the pages using Python and LibreOffice (or something).
All thoughts/directions welcome.
Kind regards,
Zoltan
--
=============================================
Zoltan Szecsei GPrGISc 0031
Geograph (Pty) Ltd.
GIS and Photogrammetric Services
Cape Town, South Africa.
Mobile: +27-83-6004028 (Signal, not WhatsApp)
www.geograph.co.za
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